1. Field of the Invention
This invention relates to a filtration process and more particularly to a process for clarifying filtration of aqueous media using filter aids added to the media to be filtered.
2. Description of the Prior Art
It is common in the filtration of industrial waste waters to use a precoated filter in which, in a preliminary step, a layer of a filter aid is deposited on a filter medium having relatively large pores, for instance a filter cloth, a filter plate, or a filter cartridge. Useful filter aids for such processes include organic materials, e.g., cellulose or synthetic fibers, and inorganic materials, e.g., kieselguhr, asbestos, bentonite, and the like. Such filter aids are commercially available, for example, under the trade names LEVASORB, AF2, SOLCA-FLOC, etc. After the filtration has been completed, the filter aid is generally burned or discarded together with the filtered solids.
This known filtering process using filter aids is expedient for the processing of normal waste water containing filterable solids, by reason of its effectiveness as well as economy. However, the known filter aids for such processes have a relatively limited efficiency, and, as a rule, tend to form a filter cake which plugs rather quickly.
Hence, a need has continued to exist for an improved filter aid which is suitable for use in filtration of industrial waste water, but does not possess the disadvantages of the known filter aids.